Great that they are getting it nailed down, though at those force levels it will struggle to find any applications - 10μN will only give about 1m/s speed increase per day to 1kg, and at that level of acceleration it would take 10 years to get from low earth orbit to the moon, 3000 years to get to Alpha Centuri. However if you are travelling 1000's of lightyears then it starts to look pretty good.

To be really useful it needs to increase in force by a couple of orders of magnitude.

Brett Bellmore wrote:

"Those tests included checking to see whether the thrusts seen depended on the pressure of the residual air in the vacuum chamber by comparing data obtained with the chamber pressure less than 10 mT with data for a chamber pressure of 10 T. ... This may take place, for example, with an object experiencing eccentric motion sitting on a rough surface, or located in a fluid with non-vanishing viscosity. In the case of this apparatus, the test that excludes residual air in the vacuum chamber eliminates the fluid varietyof Dean drive effect. "

It's an interesting implication of the kinetic theory of gasses, that the viscosity of air is independent of pressure over a very wide range. (The experimental confirmation of this was a major point in favor of the theory!) In order to actually eliminate viscous effects you would have to evacuate the chamber to a degree where the mean free path was comparable to the dimensions of the experimental setup. That's a darned good vacuum, and quite a bit better than 10mT.

This is sufficiently counter-intuitive that it's not widely understood by people who don't deal in vacuum on a regular basis.

Chad Hale wrote:

Oh, I so wish I could take a dozen of the "BIG HONKIN' ONES" to the physics dept. at ASU so the effect can be tested and studied. I could have sworn that the folks working on the mach effect thruster had two versions; a little tiny one they called the "shuttler" and the big one they labeled "warp core". I don't want to strech the limits of current technology searching for 'what might be bumps in the data of thousands of trials'. It just smacks of heaps of wrong. why?Meta analysis' can be used to prove various human psi abilities exist with far fewer trials than is needed to 'prove' the existance of the higgs boson, and further trials increasingly affirm the psi experiment results. So, we need to have very clear observations. we need to turn up the juice, we need to use a quote from commedian Tim Allen, "MORE POWER (various animal-like grunting)"....I look at the paper and say, so they turn it on briefly and hope to measure "something". Great. are we measuring lorentz effect, electromagnetic fields tugging on the metal bits, electricity heating the air, or something else that we already know? are the tests being done in a vaccum? what are the controls?What method would I want to test mach effect thrusters? FOR A FEW HUNDRED of us to put one in the boot of our car, disconect the transmission from drive train, use the Motor to power the device, and see how many miles to the gallon we get....

Robert is making a point without a point. No one thinks the current test device is a commercial prototype so the point of his little calculation seems to be self indulgence.

Brett is confused in thinking that the viscosity of the air is the issue when its not. If when you evacuate the chamber you have the same thrust signature as when its full, you know you don't have atmospheric effects. This is a control against thermal and ionic wind sources. The so called "Dean Drive effect" does not work with gasses, and the ellipsis Brett placed into the test is deliberately misleading. Brett does not deserve an answer.

Chad didn't even read the paper. The controls are explained quite sufficiently that he has no cause to ask about the kinds of spurious effects he is. The fact he claims to have read the paper and then goes on to ask about the controls that are explained, places he too into the pile of "not worth an answer".

This is the primary problem with blogs. There's no responsibility on the part of the critics. Their main intention is to prove themselves clever to the small audience they've found, not to get at the truth. There are plenty of exceptions to this rule and many are found here at T-P but I haven't ever seen any at NBF and very few at NSF.

_________________"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Last edited by GIThruster on Wed Aug 15, 2012 6:32 pm, edited 1 time in total.

There are plenty of exceptions to this rule and many are found here at T-P but I haven't ever seen any at NBF and very few at NSF.

I think you were banned from NSF long before the Propellantless Propulsion thread got more respected. There were very long, interesting, respectful discussions at that same thread, with Paul March, with many people reading all the papers, defending Mach Effect, etc.

I think you were banned from NSF long before the Propellantless Propulsion thread got more respected.

Well I posted there for 2+ years and all advanced propulsion was treated very nastily by the handful of aerospace engineers that consider NSF their private pond. It was indeed because of people like that, that I was banned. Their posts were much more aggressive and abusive than mine, but somehow they were permitted to post whatever nasty nonsense they like, and people were not permitted to respond in kind.

You're saying it's changed. Why should I believe you?

In any case, my observation stands. The people here are much more open minded than at NSF and you'd have to work long and hard to prove otherwise. After all, why did you think this forum came to exist? It came from NSF because people were fed up with the elitist nonsense there.

Sure. You can cross post my stuff at NBF. That doesn't mean I'll be responding to any responses. Been there, done that. Not worth my time, for just the reasons I've explained. In light of this, the only purpose I can see served by you cross posting is trying to start trouble, when you could just as easily make the same points I just did and those people would have the answers you seem to think they desperately need.

Or didn't you understand the answers and so can't simply provide them yourself?

_________________"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

I think you were banned from NSF long before the Propellantless Propulsion thread got more respected.

Well I posted there for 2+ years and all advanced propulsion was treated very nastily by the handful of aerospace engineers that consider NSF their private pond. It was indeed because of people like that, that I was banned. Their posts were much more aggressive and abusive than mine, but somehow they were permitted to post whatever nasty nonsense they like, and people were not permitted to respond in kind.

You're saying it's changed. Why should I believe you?

I am not saying it changed. I am saying that THE MACH EFFECT thread (Propellantless Field Propulsion) changed.

And yes, there still are some aerospace engineers there that are quite repulsive in their agressive behavior. Like Jim, who is a moderator too if I am not mistaken. He only posts very small sentences to put other people down.

Quote:

In light of this, the only purpose I can see served by you cross posting is trying to start trouble, when you could just as easily make the same points I just did and those people would have the answers you seem to think they desperately need.

Or didn't you understand the answers and so can't simply provide them yourself?

I did understood the answers. But they are small and simple enough that any attempt to provide them myself would only be different wording. But fine. I will post my own answers there.

Brett seems to have neglected the fact that the low density of the ambient gas means it responds very quickly to a given stress distribution, so the actual developed viscous stress pattern at a finite time following an instantaneous disturbance will be of minimal magnitude.

Sure, the dynamic viscosity for a given temperature is constant right down to the bottom of the continuum regime, meaning that for a given velocity shear, the stress is constant - the catch being that for external and/or transient flow, you won't see the same velocity shear because the kinematic viscosity is so high.

I am not clear on what is meant by "non-vanishing viscosity" and fluid Dean drive effects. I was under the impression that a Dean drive couldn't operate without static friction... though a non-Newtonian fluid might do...

I was under the impression that a Dean Drive couldn't operate without static friction... though a non-Newtonian fluid might do...

All the existing Dean Drives I'm aware of use the difference between static and dynamic coefficients of friction in order to operate. A couple use liquids, and in that instance alone, I think there's reason to look at viscosity. Unless I'm mistaken, the same does not apply to gasses. In any event, Jim pulls E-3T so the onus would be on Brett to demonstrate how that is not enough, when so much of industry accepts it as just fine. Any atmospheric effects ought to scale with atmosphere and the thrust signature does not.

_________________"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Robert is making a point without a point. No one thinks the current test device is a commercial prototype so the point of his little calculation seems to be self indulgence.

Self indulgent? Moi?

For my own curiosity I did some basic calculations to work out what the current results mean for space transportation, I figured others would be interested too.

James and Heidi are working hard to increase the effect and I assume also they are using the best materials they can afford for the job, yet the effect remains stubbornly small, almost at the limits of detectability.

So I think my point is valid, aside from satellite station keeping applications, and assuming the current apparatus weighs a bit less than 1kg with power supply, it appears they will need several orders of magnitude increase in the delivered force to make it really useful for space transportation - ie on the order of 1mN per kg (=86m/s per day of deltaV). That is a big performance gulf to bridge.

Based on extrapolations of current understanding and using known materials does 1mN/kg look to be achievable? Can ME drives be the answer for space exploration?

Rob, if you read the paper, you may recall from the conclusion that "then in principle it should be possible to produce the gargantuan amount of exotic matter needed to make starships and stargates technically feasible." The ability to temporarily fluctuate mass and so generate negative mass with negative inertia, is what is required for propellantless inertial drives like these under testing, for warp drives and for wormhole generators. So whether this unfunded lab test article generates enough thrust for your tastes is not the issue.

As it happens, these thrusts are 3 orders magnitude above what the ARC Lite is able to resolve, so it's hardly fair to call them "almost at the limits of detectability". The ARC Lite has low nN resolution.

In simplest answer to your question about how this might be scaled, M-E and the thrusts from M-E devices are 2 different things. IIRC, the thrusts from the current UFG design noted in this paper scale with the cube of frequency, and the frequency is limited only by the ionic limits of the material or "phase angle" that describes how quickly the ceramic can move. It is limited to the low Ghz region, so we're looking to start with an ability to scale up this thrust efficiency many orders magnitude. The current test article operates at 38kHz, so at least 5 orders magnitude frequency. The simplest reason for not building test items in the microwave region is that the electrical engineering for such power systems is really "black magic" indulged in by the best PhD EE's. Without a real staff with such people onboard, Ghz UFG's are not an option.

The thrust efficiency also scales with the cube of the k of the ceramic used. The PZT in the current test items is cheap Steiner-Martin stuff available on EBay. It has a k of about 1,000. By contrast, the PMN-15 available from TRS has a k value of ~ 20,000-25,000. Simple substitution would yield an increase of thrust of about 8,000X.

The trouble of course is, there is no such thing as "simple substitution" when you are doing a pure research program. This work reported wasn't R&D. Future work with PMN-PT will be closer to R&D, but it's important to recognize that for instance, the PZT used in the past is a piezo-active material that possesses both a 1w piezo bulk acceleration response, and a 2w electrostrictive response. The current design makes use of both of these. PMN-PT is an electrostrictor with no characterization available about it's 1w piezo response, so using it may require a new design.

When you change something like this, it's not fair to say "all things equal" as they're not. What we can and should recognize is though, that these unfunded kHz investigations with cheap materials, low frequencies and no paid engineers on staff, do not limit what M-E physics is capable of. All indications are that this technology is capable of huge thrust efficiencies that would make propellantless inertial drives ubiquitous, as well as warp drives and wormhole generators possible. All this stuff is on the table, so don't be concerned about the thrust magnitudes seen thus far.

If the thrust magnitudes reported by Paul March are any indicator, M-E thrusters are already outperforming the best Ion thrusters which require propellant. These very low thrust magnitudes jim is reporting are very close to competitive with Ion engines and it would not take much scaling to make them obsolete. Just as you say, the first market to consider is sat station keeping, and especially the Hall Thrusters used on GEO sats. The next generation of pure test articles could easily sweep them aside if they work at all.

_________________"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Overall, I would say that what is described in the paper is a refreshingly interesting and rigorous continuation of study of the Mach effect which may well lead to experimental confirmation of ideas about inertia and further our understanding of physics. I'm glad to see this proceeding nicely as genuine scientific inquiry.

Hopefully it'll also lead to a pathway for engineering a propellantless space drive, but this is good pure science, well before commercial prototypes. In that sense, although I find exciting the comment that "then in principle it should be possible to produce the gargantuan amount of exotic matter needed to make starships and stargates technically feasible," I maintain healthy skepticism until the effect is demonstrated with a good degree of certainty, and then replicated by others. First proof of concept, then scaling! Kind of like the Polywell actually...

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